That leaves the Senate’s most vulnerable Democrats veering back to the very issue that has become their biggest political liability heading into the midterms.

For now, at risk Democrats up for reelection this fall are proceeding with caution.

A spokesman for Sen. Mark Udall said the Colorado Democrat will examine Burwell’s record and hearing testimony, “as with any nominee,” before making up his mind. Shripal Shah, a spokesman for Sen. Jeanne Shaheen, said the New Hampshire Democrat “has a tremendous amount of respect for Director Burwell, her experience, and her qualifications. She’s looking forward to considering her nomination.”

Aides to Democratic Sens. Mark Pryor of Arkansas, Mark Begich of Alaska, Kay Hagan of North Carolina, John Walsh of Montana, Mark Warner of Virginia and Mary Landrieu of Louisiana all declined to respond to multiple requests for comment.

“It’s an even money proposition to be voting to replace [Kathleen] Sebelius,” one senior Senate Democratic aide said. “Whatever week or weeks the hearings or votes will take place, it’s not the topic we would choose if we could choose any topic. But it’s not bad a thing to be voting to replace Sebelius.”

Burwell’s confirmation to replace Sebelius at HHS is nearly assured. With the historic rules changes on most executive and judicial branch nominations last November, Democrats need only 51 votes to confirm her, and the party controls 55 votes in the chamber.

But if Republicans are mostly united in opposing Burwell, the support of red-state Democrats will be crucial.

Democrats hope the 96-0 vote last April for Burwell as Office of Management and Budget director, her credentials and her respected reputation will smooth the path to her confirmation. And, importantly, some moderate Senate Democrats who aren’t up for reelection are enthusiastically backing Burwell, which could give their colleagues cover to also support her.

Sen. Joe Manchin introduced Burwell – a fellow West Virginian — at both her confirmation hearings last spring, and stressed her “bipartisan relationships” in a statement praising her HHS nomination. He added that installing Burwell as HHS chief will ensure that “commonsense fixes” to Obamacare will be enacted. Sen. Heidi Heitkamp (D-N.D.) said she hoped the Senate “rallies around” the nomination of Burwell, who Heitkamp said “understands how to put good ideas to work to help families who need it.”

Sen. Angus King, a Maine independent who caucuses with Democrats, called Burwell a “brilliant choice.”

“She’ll be confirmed easily,” he said in an interview. “I’m sure that at her confirmation hearings, there will be a lot of talk about the Affordable Care Act. She’s in a great position because she doesn’t have any” baggage.

For Republicans, last year’s unanimous support for Burwell matters little in an environment where Obamacare — and how Burwell would continue the health care law’s implementation — will be the chief focus. Republican senators are sure to question Burwell on whether she’ll work with Congress on Obamacare tweaks, if the administration exceeded its executive authority with delays to deadlines in the law, and for more details on Obamacare’s enrollment numbers, GOP aides said.

The Republican message, according to one senior aide: “We would argue that there is no person on earth capable of making this horrible law work.”

Alabama Sen. Jeff Sessions, the top Republican on the Budget Committee, said Burwell has a “comparatively thin resume” to run an agency with the size and scope of Health and Human Services and indicated that he was unimpressed with her performance so far as budget director. And in an interview with Fox News on Friday, Sen. Ted Cruz (R-Texas) said Burwell’s confirmation “presents an ideal opportunity to examine the failures that are Obamacare.”

Still, for now there is little concern among Democrats that she will ultimately be confirmed — even if they get few Republican backers. So far, Sen. John McCain (R-Ariz.) is the rare Republican signaling support, tweeting that Burwell is an “excellent choice” for HHS.

Burwell will undergo hearings in both the Finance Committee and the Health, Education, Labor and Pensions committee, though the confirmation vote will be held in Finance. A committee aide said the panel’s chairman, Sen. Ron Wyden (D-Ore.), plans to schedule a hearing soon after it receives Burwell’s nomination materials. A committee mark-up seems likely in early May.

She is likely to face a full floor confirmation vote in late May or early June, since the Senate isn’t likely to shuffle its immediate schedule for her confirmation. White House press secretary Jay Carney said Friday he is anticipating a “May transition” for Burwell to HHS.

Democrats say the political environment on Obamacare has largely changed with positive enrollment numbers, which could help ease Burwell’s confirmation process. On Thursday, Sebelius — in her final Hill appearance before her resignation was made public — said more than 7.5 million people on Obamacare exchanges.

The timing is also early enough this election year to avoid the heat of the campaign season, and one Democrat noted that fierce GOP opposition may backfire if they attack a female nominee in confirmation hearings. Another fact Democrats may raise is Burwell’s leadership at the point agency during last fall’s government shutdown triggered by a fight over defunding Obamacare — a political loser for Republicans.

“She was unanimously confirmed last April to head the Office of Management and Budget, where she has proven to be an extremely effective leader who is able to work constructively with both Democrats and Republicans,” Senate Majority Leader Harry Reid (D-Nev.) said Friday. “Director Burwell deserves timely confirmation, and I hope my Republican colleagues will work with us to ensure we fill this important position without unnecessary obstruction and delay.”